We propose a new model of defect formation and ion migration at the surfaces/grain boundaries of lead-halide perovskites, based on ab initio calculations. Inspired by the spread of experimentally measured activation energies for ion migration in similar lead-iodide perovskites, we define an effective defect formation energy weighed upon surface and bulk contributions. We thus link the large variation in measured activation energies for ion migration to the different defect formation energies of polycrystalline thin films with different grains size. Defect formation is facilitated at surfaces; thus, smaller grains exhibit an averagely lower activation energy to ion migration than larger grains. We also account for the increased ion migration observed under light. Overall, our findings point at surface passivation as a major direction to stabilize lead-halide perovskites against formation of defects, limiting in turn the the associated decomposition reactions.

Formation of Surface Defects Dominates Ion Migration in Lead-Halide Perovskites

Mosconi E.;De Angelis F.
2019

Abstract

We propose a new model of defect formation and ion migration at the surfaces/grain boundaries of lead-halide perovskites, based on ab initio calculations. Inspired by the spread of experimentally measured activation energies for ion migration in similar lead-iodide perovskites, we define an effective defect formation energy weighed upon surface and bulk contributions. We thus link the large variation in measured activation energies for ion migration to the different defect formation energies of polycrystalline thin films with different grains size. Defect formation is facilitated at surfaces; thus, smaller grains exhibit an averagely lower activation energy to ion migration than larger grains. We also account for the increased ion migration observed under light. Overall, our findings point at surface passivation as a major direction to stabilize lead-halide perovskites against formation of defects, limiting in turn the the associated decomposition reactions.
2019
File in questo prodotto:
File Dimensione Formato  
2019_FormationofSurface_POSTPRINT.pdf

accesso aperto

Descrizione: Articolo principale
Tipologia di allegato: Post-print
Licenza: Creative commons
Dimensione 1.28 MB
Formato Adobe PDF
1.28 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1459917
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 222
  • ???jsp.display-item.citation.isi??? 218
social impact